Vehicle brake control means



05:.22. 1940. I 'D L,MC, ;EAL 2,218,619

VEHICLE BRAKE CONTROL MEANS Filed Aug. 51 1939 ll l'llnu l' WW??? DOY/ INV/ENTOR DONALD LMQNEAL my -v ATTORNEY Patented Oct. 22, 19 40- 2, 21 3,519

UNITED STATES PATENT OFFICE VEHICLE BRAKE CONTROL MEANS Donald L. McNeal, Wilkinsburg, Pa., assignor to V The Westinghouse Air Brake Company, Wil- V merding, Pa., a corporation of Pennsylvania Application August 31, 1939, Serial No. 292,833 I I 9 (Cl. 303-21) This invention relates to vehicle brake control .closed in the above-mentioned copending applinieans of the type adapted to automatically cation and further characterized by means for effect a rapid release of the brakes on a vehicle insuring a reapplication of the brakes after the 'wheelthat begins to slip so as to prevent sliding elapse of a certain uniform time interval followof the'wheeh ing the instant that a vehicle wheel begins to 5 As is well known, the application of the brakes slip. a on a vehicle wheelto a'degree sufficient to ex- It is another object of my invention to proceed'thelimit of rolling'friction or adhesion bevide a brake control system of thetype inditween the wheel and the road-surface or rail cated in the foregoing object wherein a novel '10 causes the wheel to decelerate rapidly to a locked arrangement is provided for causing the degree 10 or non-rotative state and slide. z of application of the brakes to be reduced below In describing. my present invention, the term a certain degree in response to initiation of a "slide refers to the dragging of a vehicle wheel wheel-slip condition before enabling reapplicaalong a road surface or a rail in a locked or nontion of the brakes to an increased degree to 5 rotative state. The term "slip is employed occur.

herein to designate the rotation of a vehicle The above objects as well as other objects of wheelat a speed less than a rotative speed cormy invention which will be made apparent hereresponding to the speed of travel of the vehicle inafter, are attained by an illustrative embodiat a given instant. The two terms slip and ment subsequently to be described and shown in go "slide" as employed herein thus refer to two the single figure of the accompanying drawing. 2

different and distinct conditions of a vehicle wheel and the distinction should be borne in m eqmment mind, Referring to the single figure of the drawing,

I It is desirable to preventa vehicle wheel, parthe equipment is h wn in diagrammatic form ticularly the wheels of a railway car or train, and, for simplicity, is illustrated in connection 25 from sliding because thewheel develops flat spots with a Single wheel-en'il-exle assembly of the necessitating replacement or repair of the wheel. conventional railway p having a Pa r 0! Wheels Various types of automatic brake control devices fixed at Opposite ends f a nne ing axle II. have accordingly been devised for the purpose of I the d w g, only One d of the axle ii d preventing the sliding of vehicle or car wheels. the Wheel at t nd are shown. 30 Typical of one type of equipment devised for pre- The a us Comprising y i vention inventing the sliding of car wheels is that described eludes brake cylinder p at e and claimed in the copending application Serial brakesassociated with'the Wheel so c of N 221,951 of Clyde C Farmer, m July 29, fluid under pressure such as a reservoir it here- 1938, and assigned to the assignee of this appliinafter referred to as the main reservoir, a man- 35 ati ually operative self-lapping type of brake valve The equipment disclosed in the above-mena P Of train P pe 6 d i1 hereinafter tioned copending application includes a rotary e d to as the supply P p and control p p inertia device that is operatively responsive to respectively, a control a v mechanism l8 cmthe rate of deceleration and acceleration of a bedyihg Certain features O y tio a V01- 40 vehicle wheel and effective to control a brake ume reservoir l8 associated with the valve mechcontrol valve mechanism. The valve mechanism anism l8,'a wheel-slip responsive device 2| assois so constructed and arranged as to instantlyand elated with the wheel-ahd-axle assembly rapidly initiate the release of the brakes on a eluding e axle l I e Wheel a Sou ce Of elec- 5 wheel that begins to slip and to continue such ic pply uch as a storage battery 2 a presrelease until such time as the degree of the sure switch 23 a a self-heldlng s ck application, exemplified by brake cylinder presy sure, reduces below a certain uniform low value C nside ng the parts of the app tus n and then effect reapplication of the brakes, that greater detail. the pp bra e valve I5 1 theresupply of fluid under pressure t th is of the well-known type disclosed andclaimed 5 brake cylinder at arestricted rate so as to miniin Patent 2,042,112 t Ewing K. y and Ranmize the possibility of a series of recurrent slipk n ush and r qui s n sp fi d ripti n ing cycles, Y thereof. Briefly, however, the brake valve l5 It is an object of my present invention to pro-- comprises an operating handle 26 effective to as vide a brake control equipment of the type (11 move a rotary operating shaft not shown that in turn effects operation of suitable valve mechanism. In the normal or release position of the operating handle 26, the control pipe H which is connected tothe brake valve l5 by a branch pipe 21 is vented to atmosphere through an exhaust port and pipe 28 of the brake valve. When the operating handle 28 is shifted in one direction from its normal release position into a so-called application zone, the valve mechanism of the brake valve device |5 is operated to supply fluid under pressure from a branch pipe 29 of the supply pipe l8 that is charged with fluid under pressure from the main reservoir l4, to the pipe 21 and control pipe l1, the brake valve being automatically self-lapping and eflective to establish a pressure in the control pipe l1 corresponding substantially to the degree of displacement oi the operating handle out of its normal position.

If for some reason the pressure in the control pipe reduces, the valve mechanism of the brake valve device I5 is effective to continue the supply of fluid under pressure to the control pipe to maintain a'pressure therein corresponding'to the position of the operating handle.

It will be understood that in the application of my invention to a train brake equipment the supply pipe Hi and the control pipe |1 extend throughout the length of the train from car to car.

The control valve mechanism l8 is'shown in extended form in a single plane but it will be understood that this is for the purpose of aiding in the comprehension of the relation of arts. In practice, the construction is such that parts shown in a single plane are in diflerent planes to secure greater compactness and minimum size of casing.

The valve mechanism 8 may comprise a casing made up of a plurality of separate sectionssuitably secured together by screws or bolts not shown. As shown, the casing of the valve mechanism |8 comprises a pipe bracket section 3| having a flange 32 adapted to be secured, as by a plurality of bolts or screws not shown, to a convenient portion of the vehicle frame. The casing 01' the valve mechanism further comprises a relay valve section 33 secured to one face 01' the pipe bracket section 3| with an intervening sealing gasket 34 therebetween and a main body section 35 secured to the opposite face or the pipe bracket section with an intervening gasket 36 therebetween. Attached to the main body section 35 is a cover section 31 with a gasket 38 interposed therebetween. J

Formed in the pipe bracket section 3| is a volume reservoir 4|, the purpose of which will be made apparent hereinafter, a bore or chamber 42 in'which is contained a filter or strainer 43, and various communicating passages hereafter described.

The arrangement is such that all pipe connections to the valve mechanism |8 are made at the pipe bracket section 3|. Thus the relay valve I section 33 and the main body section 35 may be severally removed from the pipe bracket section 3| without disturbing the pipe connections to th valve mechanism.

The relay valve mechanism embodied in the I relay casing section 33 is of the super-sensitive high-capacity type disclosed and claimed in Patent 2,096,491 to Ellis E. Hewitt and in itself is not my invention. Briefly, the relay valve mechanism comprises a main supply valve 45, a pilot supply valve 46, a main release valve 41 and a pilotrelease valve 48, which valves are operated by means of operating lever 49 pivoted at a point between the ends thereoi on the stem 5| of an operating piston 52;

Formed at one side of the operating piston 52 is a control chamber 53 and on the opposite side of the piston 52 a pressure chamber 54.

When fluid under pressure is suppliedto the control chamber 53 through a passage 55 in the manner subsequently to be described, 'the piston is urged upwardly'to eflect operation of the main release valve 41 and main supply valve 45 in succession to supplyfluid under pressure from they to effect reseating of the main supply valve 45' Thus without unseating the release valve 41. the pressure established in the brake cylinder l3 corresponds to the pressure established in the control chamber 53.

When the fluid-under pressure in the control chamber 53 is released in the manner hereinafter to be described, the higher pressure in the pressure chamber 54 shifts the operating piston 52 downwardly to efl'ect unseating of the main release valve 41 and the consequent release of fluid under pressure from pressure chamber 54 and brake cylinder l3 to atmosphere through an exhaust passage and port 58.

Volume reservoir I8 is connected into the passage 55, as shown, to provide sumcient operating volume for the control chamber 53.

Embodied-in the main casing section 35 are a magnet valve device 5|, a reapplication control valve device 82, an inshot valve device 53 which is provided as a particular feature of my invention for insuring the reapplication of the brakes and operative only a certain predetermined time after the slipping of a car wheel begins, a doublecheck valve 64, and two one-way or check valves and 86 respectively.

The magnet valve device 8| comprises a double beat valve 68 which is urged to an upper seated position by a coil spring 68 and to a lower seated position in response to energization of an electromagnet winding or solenoid 1|. beat valve 68 is contained in a chamber 12 in the casing section 35 and with the double-beat valve 68 in its upper seated position as shown, communication is established past the lower valveseat between the chamber 12 and another chamber 13.

When the double-beat valve 88 is in its lower seated position, communication between the chambers 12 and 13 is closed and communication is opened past the upper valve seat of the valve 68 between the chamber 12 and a chamber 14 'that is constantly open to atmosphere through chamber 83 and a chamber 84. The valve 18 is yieldingly urged toward seated relation on an as- The double sociated valve seat formed on the wall 82 by a coil spring 88 that is interposed between the valve and a screw plug closing the chamber 88.

Chamber 84 is connected by a passage 89 to a passage 81, hereafter called thesupply passage, thatleads to the outlet side of the filter 43 in the bracket section 8|. The inlet side of the fllter is connected through a passage to the control pipe I1. The chamber '88 is connected by a passage" containing a chokeelement 89 therein to the supply passage 81, and also bya branch passage 9I opening out of the passage 88, at a point between the chamber 88 and choke element 89, to the chamber 18 of the magnet valve device 8|.

The operating piston 19 of the valve device 82 is annular in form and is provided with a hollow stem 98 that is closed at its outer end and provided thereon with a projecting'knob 94 that extends into the chamber 84 and engages the end of the fluted stem of the valve 18. The piston 19 operates in a suitable bore 98 that opens at the face of the casing section 89covered by the cover section 81, a portion of the gasket 88 overlapping the bore and forming a seat portion on which the piston 19 is adapted to be seated when shifted upward from the position in which it is shown. The hollow stem 98 of the piston 19 is guided in a suitable bore 98, of smaller diameter than the bore 95, that is in open communication with the chamber 84.

Formed between the piston 19 and the cover section 81 is a chamber 98 that is connected by a branch passage 99 to a passage I9I that opens into the chamber 12 of the magnet valve device 8|. Formed at the opposite side of .the piston 19 is an annular chamber I92 that is constantly open, through suitable grooves I98 in the stem 98 of the piston, to the chamber 84.

A coil spring I98 is interposed between the cover section 81 and the inner surface of, the closed end of the piston stem 98 and normally urges the'piston downwardly into seated engagement on a shoulder formed between the two bores 98 and 99, in which position the knob 94 engages the fluted stem of the valve 18 and unseats the valve 18 from its associated valve seat.

Associated with the piston 19 and contained in a chamber I98 formed in the cover section 31 is'an exhaust valve I91 of the poppet type. Valve I91 is normally yieldingly urged into seated relation on an associated valve seat by a coil spring I88 that is interposed between the valve and a .plug I89 screwed in the open end of the chamber I98 and having an exhaust port II9 therein. Valve I91 has a fluted stem III that extends through a suitable port or'passage in the casin section 81 to the chamber 98 at the upper side of the piston 19 and is adapted to be engaged by the upper end of a pin -I I2 that is attached to or formed integrally with the closed end of the piston stem 98 and extends upwardly through the hollow stem 93. With the piston 19 in its lower position as shown, the upper end of the pin I I2 has a slight clearance with respect to the end of the fluted stem III of the valve I 91 and accordingly the valve I91 is seated. When the piston 19 is shifted upwardly, in the manner subsequently to be described, the pin 2 eflects the unseating of the valve I91 and communication is thus established from the chamber 88 tothe chamber I98. Fluid under pressure is thus vented from the chamber 98 to atmosphere through the exhaust port H9 in the screw plug I99.

It will be apparent that as long as the fluid pressures in the two chambers 98 and I92 at the opposite sides of piston 19 are substantially equal, the spring I99 is eifective to maintain the valve 18 unseated. If the pressure of the fluid in the chamber 98 is suddenly reduced, which as will be subsequently seen is effected by operation of the magnet valve 8|, the higher pressure in thechamber I92 overcomes the force of the spring I98 and shifts the piston 19 upwardly into seated relation on the seat portion of the gasket 88 so that the valve 18 is seated and the valve I91 is unseated.

With the valve I91 unseated and the piston 19 seated on the seat portion of the gasket 88, the portion of the chamber 98 within the inner seated area of the piston is constantly main is seated onthe seat portion of the gasket 88, until the pressure in the chamber I92 reduces below a certain uniform low pressure such as flve pounds per square inch.

-As will be made more apparent hereinafter, this characteristic operation of the valve device 82 is adapted to render the choke element 89 eflective to restrict the rate of resupply of fluid under pressure to the brake cylinder I8 after a wheel slip condition is relieved by release of fluid under pressure from the brake cylinder.

The inshot valve device 88 comprises a valve piston II! that operates in a suitable bore 8 formed in the casing section 85 and opening at the face coveredby the cover section 81. A coil spring II1 interposed between the valvepiston iii and the coversection 81 normally urges the valve piston inwardly of the bore II8 into seated relation on an annular gasket seat II8 suitably secured at the lower end of the bore. With the valve piston II seated on the gasket seat II9, the outer seated area of the valve piston is open to and subject to the fluid pressure in the supply passage 81 while the inner seated area of the valve piston is open through a suitable port II9 to a chamber I29.

Associated with the valve piston H5 is a valve I22 of the poppet type that has a iluted'stem I28 which extends through the port H9 and is adapted to be engaged by the face of the valve piston III. The valve I22 is contained in a chamber I24 and is urged toward seated relation on an associated valve seat, formed on a wall I28 separating the chambers I24 and I29, by a coil spring I28 which is interposed between the valve I22 and a plug I21 screwed in the open end of the chamber I24. The screw plug I21 has an exhaust port I28 therein and thus the chamber I24 is constantly at atmospheric pressure.

With the valve piston I|5 seated on the gasket seat II8, the valve I22 is unseated against the force of the spring I28 and thus the inner seated area of the valve piston H8 is maintained at atmospheric pressure.

The chamber I8I formed in the bore H8 at the back side of the valve piston I I 5 is connected by a passage I82 containing a restriction or choke I88 to a branch passage I84 of the passage IN.

r .n a

the fluid in the supply passage 81.

The chamber III is also connected to the volume chamber 4I in the'pipe bracket section II of the casing by a'branch passage I which opens out of the passage I22 at a point between the choke I32 and-chamber III. The passage I22 contains a restriction or choke I21, the-purpose of which will be made apparent hereinafter.

It will be noted that one-way valve device is arranged in parallel relation to the choke I 23 in a manner to permit the flow of fluid under pressure from-the passage III to the passage I22 and chamber I2I at a rapid rate and to prevent the reverse flow of fluid under pressure therepast. The one-way valve device 65 is in reality two serially related one-way valves, one of the ball valve type and the other of the spring-loaded disk type.

As will be subsequently described. in greater detail, when an application of the brakes is initiated fluid under pressure is supplied simultaneously to the outer seated area of the valve piston H5 and to the chamber III at the back side of the valve piston, and accordingly, the spring III maintains the valve piston seated on the gasket seat II8. Due to the connection of the chamber I3I to the passage IIII, the actuation of the double beat valve 68 of the magnet valve device 6| to its lower seated position in response to energization of the magnet winding II causes the venting of fluid under pressure from the chamber I 3|.

The capacity of the volume chamber H is such however in relation to the size of the choke I 3! in the passage I32 as to restrict the reduction of pressure in the chamber I3I to a predetermined rate. Accordingly, the valve piston H5 is not shifted upwardly away from the gasket I I8 until the pressure in the chamber I3I has reduced sufllclently in relation to the fluid pressure acting on the'outer seated area of the valve piston, and such reduction does not occur until a certain uniform time, such as ten seconds, has elapsed following the beginning of the reduction of the pressure in thechamber I3 I. The purpose of this delayed operation of the inshot valve device 63 will be made apparent hereinafter.

'When the pressure in the chamber I 3| at the back side of the valve piston I I5 is sufiiciently reduced, the fluid pressure acting on the outer seated area of the valve piston overcomes the force of the ,spring H1 and starts to shift the valve piston upwardly. As the valve piston H5 moves upwardly, the valve I22 is correspondingly shifted to seated position by the spring I 26 to prevent the, exhaust of fluid under pressure therepast and, at the same time, the entire face of the valve piston H5 is subjected to .the pressure of Accordingly, the valve piston H5 is snapped suddenly and rapidly upwardly into seated relation on a seat portion of the gasket 38 that overhangs the opening of bore H6.

With the valve piston H5 in its upper-seated position, the supply passage 81 is connected by way of the port I I9 to chamber I20.

The double-check valve device 54 is of conventional type comprising a shiftable piston valve 64a that is ,subject on the upper end thereof to the pressure of fluid supplied through branch passage I34 of the passage IIII and on the lower end thereof to the pressure of. the fluid supplied through a passage I2I from chamber I20.

In the arrangement shown, the piston valve 54a is shiftable in a vertical bore and is thus normally urged by gravity to its lower seated position. This arrangement is, however, notessential be horizontal. v

With the piston valve 64a in its lower seated position, a'port MI is uncovered to connect the passage 55 to the bore at the upper side of the piston valve 64aand thus communication is established between the passage I34 and the passage 55.

If the pressure of fluid supplied through passage I2I to the lower end of the piston valve 840 exceeds the fluid pressure acting on the upper end of the piston valve 64a, the piston valve is shifted upwardly to an upper seated position. In this position, port I is covered and a port I42 is uncovered to connect the passage 55 to the bore at the lower side of the piston valve, thus establishing communication between the passage I2I and the passage 55 while at the same time cutting oil communication between the passage I34 and the passage 55.

The one-way or check-valve device 66, like theone-way valve device 65, comprises two serially related check valves, one of the ball type and theother ofthe disk type. Check valve device 68 is contained in the cover section 31 and is interposed in the passage 55 at a-point between'the port I of the double'check valve device 64 and the outer seated area of the valve piston of the inshot valve device 83. The arrangement of the checkvalve device is such as to prevent the supply of fluid under pressure therepast from the supply passage 81 to the passage 55 leading to the control chamber of the relay valve mechanism while effective to permit free and rapid flow of fluid under presthe control chamber 53 independently of thecondition of the reapplication valve device 62.

The wheel-slip responsive device 2| is illustratively shown as of one of the types disclosed and claimed in the copending application Serial No. 219,616 of Clyde C. Farmer, filed July 16, 1938, and assigned to the assignee of this application. It should be understood however that any other suitable type of wheel-slip responsive switch device may be employed.

, The wheel-slip responsive device 2I is described in detail in the copending application referred to and needs no specific description herein. Briefly, however, the device comprises a fly-wheel (not shown) which is driven by rotation of the axle ll through a resilient yielding connection that enables the fly-wheel to overrun or lag the axle II and thus shift forwardly or backwardly of a certain normal position. This movement of the fly-wheel relative to its normal position is adapted to efiect longitudinal movement of a finger I45 which is in coaxial relation to the axis of the axle II to efiect the engagement of two normally disengaged contact fingers 6 that are carried on an insulating block I41. The insulating block I" is secured to a bracket I48 that is secured to the axle journal housing I49.

a's'tl'ie bore containing the piston valve 64a may it will be seen that contact fingers I45 are not actuated into engagement with each other unless the car wheel I2 slips.

The self-holding relay 24 is a conventional type of relay and, as illustrated diagrammatically, comprises a magnet winding I5I effective when energized to actuate an armature so as to shift a contact member I52 on the armature from a circuit-open to a circuit-closed position. When the magnet I5I is deenergized, the contact member I52 is biased to circuit-open position by gravity or a spring not shown.

The pressure switch 23 is of conventional type and, as diagrammatically shown, comprises a casing containing a piston I53 having a stem I54 that carries in insulated relation thereon a contact member I55. At one side of the piston I53 is a coin spring I55 which urges the piston to' a lower-seated position in which the contact member I55 disengages from a pairof associated contact members I51. On the side of the piston I53 opposite the spring I55 is a chamber I58 into which the pipe 55 leading to the brake cylinder is connected.

The force of the spring I55 is such as to maintain the contact member I55 disengaged from its associated contact members I51 as long as the pressure in the brake cylinder and supplied to the chamber I58 does not exceed a certain low pressure such as fifteen pounds per square inch.

4 When the pressure in the brake cylinder acting on the piston I53 of the pressure switch exceeds the fifteen pounds per square inch, the piston is snapped upwardly to effect engagement of the contact member I55 with its associated contact members I51. The contact member I55 is thereafter maintained in engagement with the contact members I 51 as long as the pressure in the brake cylinder is suflicient to overcome the spring I55. When the pressure in the brake cylinder reduces sufficiently below fifteen pounds per square inch, the spring becomes efiective to shift the piston back to its lower seated position, thus again disengaging the-contact member I55 from the contact members I51.

The control circuits whereby the wheel-slip responsive device 2| controls the magnet winding ll of the magnet valve device 5| as well as the relay 24 will be described hereinafter in connection with an assumed operation.

Operation Assuming that the main reservoir I4 is suitably charged to the normal pressure carried therein by a fluid compressor not shown and that the vehicle is traveling along the road with the brake valve handle 25in its normal release position so that the brakes are released, the operator may effect an application of the brakes by shifting the brake valve handle 25 into the application zone an amount corresponding to the desired degree of application of the brakes.

With the brake valve handle 25 in application position the control pipe I1 is charged to a pressure corresponding to the position of the brake valve handle. Fluid under pressure is accordingly supplied from the control pipe I1 through the filter 43, passages 81 and 85, chamber 84, past the unseated valve 18 of the reapplication control valve device 52, chamber 83, passage 88, passage 3I, chamber 13, past the lower valve seat of the double beat valve 55 of the magnet valve device 5|, passage IOI, branch passage I34, port I4I of the double-check valve device 54 which is uncovered, and passage 55 to the control chamber 53 of the relay valve device.

The relay valve device is' thus operated to supply fluid under'pressure through the passage and pipe 51 to the brake cylinder I3 to establish a pressure therein corresponding to the pressure established in the control chamber 53. Assuming that the pressure established in the brake cylinder isof the order of twenty-five pounds per square inch, the pressure switch 23 is thus actuchamber 84, the spring I05 maintains the piston 13 in its lower seated position shown.

Fluid'under pressure flows at a rapid rate from the passage II'II past the one-way valve device 55 and through the passage I32 to the chamber I3I at the back side of the valve piston II5 of the inshot valve device I53, at the time that fluid under pressure is being supplied to the on trol chamber 53. Due to the resulting rapid build-up of fluid pressure in chamber I3I, the

pressure of the fluid supplied simultaneously from passage 81 and acting on the outer seated area of the valve piston I I is ineffective to unseat the valve piston. Accordingly, the exhaust valve I22 remains unseated and the lower end of the piston valve 54a of the double check valve device 54 is vented to atmosphere through the exhaust port I28 and is maintained positively in such position by the pressure of the fluid acting on the upper. end of the piston valve 54a supplied through the passage I34.

The volume chamber 4I' in the pipe bracket 8 section 3|, being connected to the chamber I3I' in the manner previously described, is likewise charged to the pressure established in the chamber I3I. In order to insure the rapid build-up of pressure in the chamber I3I, the choke I31 is interposed in the passage I35 leading to the volume chamber 4I so that the relatively large volume of chamber M will not delay the build-up of pressure in the chamber I3I. It will be apparent that the pressure in the chamber I3I must be built up sufficiently rapidly to prevent the unseating of the valve piston H5 in response to the supply of pressure through the supply passage 81 to the outer seated area of the valve piston I I5.

With the brake cylinder I3 charged to the assumed pressure of twenty-five pounds per square inch, the brakes are accordingly applied to the car whels I2 with a corresponding degree of force.

If the operator desires to increase or decrease the degree of application of the brakes, he merely shifts the brake valve handle 25 farther from or nearer the normal release position to correspondingly vary the pressure in the control chamber 53 of the relay valve device, which in turn effects a corresponding variation of the pressure in the brake cylinder I3.

If the operator desires to release the brakes, he merely shifts the brake valve handle 25 to its normal release position and thus causes fluid under pressure to be vented from the 'control pipe I1 to atmosphere through the exhaust port and pipe 28 at the brake valve I5. It will be noted that upon a reduction of the pressure in the control pipe I1, the fluid under pressure in the control chamber 53 and the connected volume reservoir I9 may flow from the passage 55 past the one-way valve 66 to the passage 81 and then reversely through the filter 43 to the control pipe I 1, thus assuring the rapid reduction of the pressure in the control chamber 53 of the relay valve mechanism in correspondence with the reduction of the pressure in the control pipe I1.

As long as the reapplication control valve device 62 remains in the position shown, with the valve 18 unseated, fluid under pressure may also flow reversely from the control chamber 53 of the relay valve device through the pipe 55, port I4I of the double-check valve device 64, passages I34 and IOI past the lower valve seat of the double beat valve 68 of the magnet valve device 6I, chamber 13, passages SI and 38,. chamber 83, past the unseated valve 18, chamber 84, passages 86 and 81, and through the filter 43 to the control pipe I'I.

With the pressure in the control chamber 53 of the relay valve device reduced to atmospheric pressure, the fluid under pressure in the brake cylinder I3 is correspondingly vented to atmosphere through the exhaust passage 58 of the relay valve device.

If the degree of application of the brakes effected in the manner above described is such that the car wheel I2 begins to slip, a further operation of the control valve mechanism I8 occurs due to the energization of the magnet winding H of the magnet valve device 6I in response to the engagement of the contact fingers I46 of the wheel-slip responsive device 2I. The engagement of the contact fingers I46 of the wheelslip responsive device 2I completes a circuit for energizing the magnet winding H of the magnet valve device 6I and the magnet winding of the relay 24. This circuit extends from one terminal of the battery 22, hereinafter referred to as the positive terminal, by way of a wire I6I, a branch wire I62, the contact fingers I46, and a Wire I63 to the point I64, where the circuit divides into two parallel branches, one branch extending by way of the wire I63 and magnet winding H of the magnet valve device 6| to the negative terminal of the battery 22 as through a ground connection indicated, and the other branch extending from the point I64 by way of a branch wire I65, magnet winding I5I of relay 24, and to the negative terminal of the battery 22 as through a ground connection indicated.

Once the relay 24 is energized and its contact member I52 actuated to closed position, a holding circuit is established for maintaining the magnet winding I 5| of the relay 24, as well as the magnet winding H of the magnet valve device 6i, energized thereafter independently of the wheel-slip responsive device 2|.

The holding circuit just referred to extends from the positive terminal of the battery 22 by way of the wire I6I, contact members I51 and I55 of pressure switch 23, a wire I61, contact member I52 (now closed) of relay 24, and then through two parallel branches, one of which includes the magnet winding of the relay 24 and the other of which includes the wires I65 and I64 and the magnet winding H of the magnet valve 6!, both branch circuits returning to the negative terminal of the battery 22 in the manner previously described.

When the magnet winding H of the magnet valve device 6| is energized in the manner just L ing circuit.

described, the double beat valve 68 is operated to its lower seated position to cut off the communication previously described through which fluid under pressure is supplied to the control chamber 53 of the relay valve deviceand'at the 5 same time establish communication through which fluid under pressure is rapidly vented from the control chamber 53. This exhaust communication extends from the control chamber- ,53 through the passage 55, port I4I of the dofible 10 check valve device I64, passages I3 4Y and; IIJI, chamber 12 of the magnet valve device sup-as: the upper valve seat of the doublerbeatwalye 68, chamber 14, passage 15 andto -atmo'sp e through the choke element I16. Choke element 15 4 H6 is of such size in relation to the combined volume of thecontrol chamber 53 and volume reservoir I9 as to effect a rapid reductio'n'of pressure in the control chamber 53., I At the same time, fluid under pressure i sYalso exhausted from the chamber 98 above the piston 19 of the reapplication control valve device-62 1 due to the connection between the chamber 98 and the passage IOI through branch passage 99. The piston 19 is accordingly shifted suddenly and positively to the upper seated position on the seat portion of the gasket 38 and thus unseats the valve I01 and seats the valve 18. Assuming a pressure such as twenty-five pounds per square inch to have been established in the ,control pipe I1, the piston 19 is, as previously explained, thereafter maintained in its upper seated-position.

The exhaust of fluid under pressure from the control chamber 53 of the relay valve device through passage I34 also causes a reduction "of the fluid pressure in the chamber I3I of,j; infill-( 11?, valve device 63 and the connected 'vlume' ber H. The choke I33 in the passastricts the rate of exhaust of the fiuid pressure from the chamber I3I and volume chamber 4| to passage I34 and thusvalve pistii ;I"I5 of the inshot valve device 63 is not immediat ly shifted upwardly to its upper seated positio Upon the rapid reduction of the pressure, control chamber 53 of the relay valve'de'v relay valve device is correspondingly ope'r rapidly exhaust fluid under pressure from the brake cylinder I3 through the exhaust passage and port 58. This reduction of the pressure in the brake cylinder I3 is effected so rapidly in response to the initiation of the slipping of the wheel I2 that the wheel does not decelerate completely to a locked or non-rotative state but promptly ceases to decelerate and beginsto accelerate back toward a rotative speed corresponding to the speed of the vehicle.

The purpose of the holding circuitlshouldnow be apparent for, when the car wheel I2 changes from deceleration to acceleration, the contact fingers I46 of the wheel-slip responsive device 2| are momentarily opened and thus deenergization of the magnet winding H of the magnet valve device 6I would be effected except for the hold- It will thus be apparent that'hs long as the pressure switch 23 remains closed, 55 the magnet winding 'II of the magneti valve' fi'l remains energized and fluid under pressure cgn tinues to be exhausted from the control chamber ing H of the magnet valve device 6| becomes de-' energized so that the double beat valve 68 of the magnet valve device 6| is correspondingly returned to its upper-seated position closing the exhaust. communication and reestablishing the communication through which fluid under pressure is supplied to the control chamber 53 of the relay valve device.

- Due to-the .fact that the piston 19 of the reapplication control valve device 62 is pneumatically stuck or maintained in its upper seated position, however, the valve 18 remains seated and thus prevents; the supply of fluid under pressure therepastiirom the supply passage 81 to the chamber 13 of the magnet valve device 6|, ac:- cordingly, fluid under pressure is resupplied from the supply passage 81 to the control chainber 53 of'the'relay valve device only by way of the portion of passage 88 including the choke 89, branch passage 9|, chamber 13 of the magnet valve device 6|, and thence past valve 68, through the passages HH and I34, port |4| of the doublecheck valve device 64, and passage 55.

It will thus be seen that once the car wheel l2 begins to slip, the rate of resupply of fluid under pressure to the control chamber 53 of the relay valve device is restricted to a rate determined by the flow area of the choke element 89. As a result of the restricted rate of resupply of fluid under pressure to the control chamber 53 of the relay valve device, the pressure in the brake cylinder I3 is correspondingly restored at a restricted or slower rate and, depending upon the flow area of the choke element 89, may or may not be restored to the initial pressure which caused the car wheels to begin to slip, before the car or train is completely stopped. The flow area of choke element 89 is preferably of such size that the pressure established in the control pipe I1 is not restored in the control chamber 53 of the relay valve device until after the car is brought fully to a rotative speed corresponding to vewheel'slipping of the car wheel I2 is rendered hicle speed and thus, when the pressure switch 23 does open, the wheel-slip responsive switch for energizing the magnet valve device GI and; the relay 24 because the contact fingers 6' thereof are separated. The fact that the brake. cylinder pressure is not reduced sufficiently to open the pressure switch 23 until after the slipping wheel returns fully to a rotative speed corresponding to vehicle speed accordingly prevents the resupply of fluid under pressure to the brake cylinder and consequently the reapplication of the brakes prior to the restoration of the car wheels to a rotative speed corresponding to vehicle speed. Thus the possibility of recurrence further unlikely because the reapplication of the brakesthereon cannot be initiated while the car wheel is slipping and rotating; at a relatively; low speed. I The time interval which elapses from the time.

that the car wheel begins to slip until it is re- "in'the manner just described is'iof the order of two or three seconds. If for some reason, such as the sticking of the double beat valve 68 of magnet valvedevice 6| in its lower seated position notwithstanding deenergization thereof, the resupply of fluid under pressure to the control chamber 53,..of the relay valve device and ,consequently the resupply of fluid under pressure of the brake cylinder l3 does not take place within such interval of time, the continued reduction of the pressure in the chamber |3| and theconnected volume chamber 4| causes the valve piston N5 of the inshot valve device 63 to be shifted upwardly"t'o its upper "seated position in which fluid under pressure is supplied directly from,

the supply passage 81 to the, lower end of the piston valve 64a ofthe double check valve device 64. Since the pressure in the passage I34 and connected passage is relatively low due to the exhaust communication through the choke I6,

the higher pressure supplied to the lower end of the piston valve 64a of the double, check valve device'64 shifts the piston valve upwardly to uncover the port I42 and close theport |4|. Thus the piston valve 64a is operated to close the exhaust communication from the=passage 55 and the control chamber 53 of the relay valve device and, at the same time, establish a supply communication through which fluid under pressure is supplied directly from the supply passage 81' past the unseated valve piston N of the inshot valve device 63 and. through the port I42 of the double check valve device 64 to the passage 55, thus causing the fluid pressure in the control chamber 53 of the relay valve device to be rapidly restored to the pressure established in the control pipe The relay valve device correspond ingly operates to immediately build up the pressure in the brake cylinder l3 to reapply the brakes on the car wheel l2. I

It will thus be seen that if the magnet valve device 5| operates properly in response to demergization of its magnet winding H, the inshot valve device 63 is not operated because the pressure in the chamber |3| at the back of the valve piston H5 of the inshot valve device 63 begins to be built up again before beingreduced sufliciently to cause upward movement of the valve piston to its upper seated position. The inshot valve 63 is operative, therefore, toinsure the ,resupply of fluid under pressure to the brake cylinder following release caused by a slipping of thecar wheel only in the event that the magnet valve device 6| does not operate properly to effect such resupply.

The inshot valve device functions also upon the initial application of the brakes if the double beat valve 68 of the magnet valve device 6| happens to be stuck in its lower seated position preventing the supply of fluid underpressure therepast from the supply passage .81 to the control chamber 53 of the relay valve device. It will be apparent that this is so because if fluid pressure is not built up in the chamber |3|j due tothe double beat valve 68 of the magnet 'va'lve 6| being stuck in the lower seated position, the fluid under pressure supplied to the outer-seated area of the valve piston ||'5 from the passage 81 unseats the valve thus to the control chamber 53 or the relay valve device independently of the magnet valve device 5|. j I

As previously stated, the delay in effecting reapplication of the brakes following slipping of the [car wheel 2 as well as the restoration of the brake cylinder pressure at a restricted rate renders unlikely a recurrence of wheel slipping. Ii, however, the car wheel i2 should again begin to slip following the reapplication of the brakes,

the magnet valve device 6| is again operated to exhaust fluid under pressure from the control chamber o! the relay valve device to eiiect corresponding reduction of the pressure 01' the brake cylinder II and, after the brake cylinder pressure reduces sufliciently to open pressure switch 23, to effect reapplication of the brakes at the restricted rate. In this instance, however, the piston 19 of the reapplication control valve 62 is not operated since it has remained in its upper seated position due to the previous slipping of the wheel.

It will thus be apparent that although the reapplication of the brakes eflected in response to the operation of the inshot valve device 63 is not at a restricted rate, nevertheless constant protection against the sliding of the wheel is maintained and at no time can the car wheel attain a locked or sliding state.

When the vehicle comes to a stop in response to an application of the brakes'during which slipping of the car wheel I! occurs, the brakes may be released, prior to again starting the vehicle, by shifting the brake valve handle 26 to its normal brake release position. Inthis instance, assuming that the inshot valve 63 has not operated, fluid under pressure wouldbe released from the control chamber 53 of the relay valve device only at a restricted rate determined by the flow area of choke element 89 except'for the oneway valve 66. The one-way valve 66 permitting, as it does, V

the direct flow of fluid under pressure from the passage 55 to the passage 8'! independently of the seated position of the valve 18 of the reapplication control valve device 63 permits a normal rate of release of the brakes and prevents an unduly long release time.

If the inshot valve device 63 has been operated, fluid under pressure may be rapidly released from the control chamber 53 through the passage 55 to the passage 81 past the unseated valve piston i i5 of the inshot valve 63 until such time as the pressure in the passage 81 reduces sufiiciently to permit the spring Ill to shift the valve piston H5 to its lower seated position on the gasket seat .i it. Thereafter, except for the one-way valve 66, the only release communication would be by way of the choke 89. Thus the one-way valve 66 is also effective in such instance to enable a normal release time.

With the double beat valve 68 of the magnet valve 6| improperly held in its lower seated position after the valve piston I I5 of the inshot valve device 63 is reseated on the gasket seat 8, a certain amount of pressure would remain trapped in the control chamber 53 of the relay valve mechanism so that a corresponding pressure would remain in the brake cylinder l3. Thus the brakes might remain applied to a certain degree and drag. In this instance, however, the one-way Summary Summarizing, it will be seen that I have dis-' closed a vehicle brake control equipment including a wheel-slip responsive device and a control valve mechanism that is efiective under the control of the wheel-slip responsive device, when a .wheel begins to slip, to initiate a rapid reduction of the pressure in the brake cylinder applying the brakes on the slipping wheel and, thereafter, to effect reapplication of the brakes on the slipping wheel at a restricted rate only when the pressure in the brake cylinder reduced below a certain low value,'which amount of reduction does not occur until after the slipping wheel has been again restored to a rotative speed corresponding to vehicle speed.

According to my invention, the equipment disclosed further includes a so-called inshot valve device which is effective to insure a reapplication oi the brakes if a certain time, such as six seconds elapses after a wheel begins to slip without operation of the control valve mechanism in its accustomed manner to effect the reapplication of the brakes. The inshot valvedevice is also effective in the event of sticking of certain valve parts of the control valve mechanism to insure an application of the brakes when first initiated.

While I have illustrated and described my invention in connection with a single pair of wheels, the manner in which it may be adapted to the control of all the pairs of wheels on a car or train will be readily apparent. Also, various omissions, additions and modifications may be made in the specific embodiment shown without departing from the spirit of my invention. It is accordingly not my intention to limit the scope of, my invention except as it is necessitated by the scope of the prior art.

Having now described my invention, what I claim as new and desire to secure by Letters Patcut is 1. Vehicle brake control apparatus comprising, in combination, manually operated means for controlling the application and release of the brakes associated with the wheels of the vehicle, means operatively responsive to slipping of a vehicle wheel, means controlled by the wheel-slip responsive means for automatically effecting a rapid release of the brakes associated with the wheel independently of the manually operated means when the wheel begins to slip and effective thereafter, in its normal manner of operation, to initiate the reapplication of the brakes on the wheel within a certain length of time following the instant the wheels begin to slip, and means automatically effective to initiate reapplication of the brakes on the wheel in the event that the last said means fails to initiate reapplication within said certain length of time.

2. Vehicle brake control apparatus comprising,

in combination, manually operated means for controlling the application and release of the brakes associated with the wheels of the vehicle, means operatively responsive only to the changes in rotative speed of a vehicle wheel at a rate in excess of a certain rate, means controlled by the last said means for automatically efi'ecting release of the brakes associated with the wheels. independently of the manually operated means when the wheel begins to decelerate at a rate in excess of said certain rate and'eifective thereafter, in its normal manner of operation, to initiate reapplication of the brakes on the wheel within a certain length ofv time following the instant the wheel begins to decelerate in excess of said certain rate, and means automatically effective to initiate reapplication of the brakes on the wheel in the event of failure of the last said means to initiate reapplication of the brakes within said certain length of time.

3. Vehicle brake control apparatus comprising, a combination, manually operated means controlling the application and release of the brakes associated with the wheels 01' the vehicle.

means operatively responsive to the slipping oi a vehicle wheel, means set in operation under the control of the last said means when the vehicle wheel begins to slip for automatically effecting a rapid release of the brakes on the wheel independently of the manually operated means and thereafter, in its normal manner of operation, initiating reapplication of the brakes on the wheel only after the application of the brakes has been reduced below a certain degree, and means effective upon the expiration of a certain uniform time after the instant the wheel begins to slip, to initiate reapplication of the brakes on the wheel in the event that the last said means fails to initiate reapplication of the brakes within said certain time.

4. Vehicle brake control apparatus comprising, in combination, means providing a chamber, means effective in accordance with the fluid pressure established in said chamber for effecting a corresponding degree of application of the brakes on a wheel of the vehicle, means providing a communication through which fluid under pressure is supplied to said chamber and released therefrom, valve means normally efiective to permit fluid under pressure to be supplied through the communication to said chamber and operative to a different position to prevent the supply of fluid under pressure through the communication to the said chamber and at the same time to vent fluid under pressure from said chamber to effect a reduction of pressure therein resulting in a release of the brakes, means effective when a wheel begins to slip to cause operation of said valve means to its said different position and effective when the application of the brakes has been reduced below a certain degree to cause restoration of said valve means to its normal position, a valve device operative to supply fluid under pressure to the-said chamber independently of the said valve means, and means for causing operation of said valve device to supply fluid under pressure to the said chamber if said valve means remains in its said different position longer than a certain length of time.

5. Vehicle brake control apparatus, comprising in combination, means providing a chamber, means effective according to the fluid pressure established in said chamber for causing application of the brakes on a wheel of the vehicle to a degree corresponding to the pressure in said chamber, means providing a communication adapted to be charged with fluid at a pressure corresponding to a desired degree of application oi! the brakes; valve means efl'ective'normally in one position to permit fluid under pressure to flow from said communication to said chamber and operative to a different position to prevent the flow of fluid under pressure from said communication' to said chamber and at the same time to exhaust fluid under pressure from said chamber, a valve device including a movable abutment adapted to be subject on one side to the pressure in said communication and on its other side to the pressure in said chamber, said valve means being effective in its said different position to cause a reduction of the pressure on the other side of said valve device, and means for so controlling the rate of reduction of the pressure acting on the said other side of the abutment of said valve device as to cause,

movement of the said abutment resulting in operation of the said valve device to establish a communication through which fluidunder pressure is supplied to said chamber from said comchamber, means providing a communication adapted to be charged with fluid at a pressure corresponding to a selected degree of'application of the brakes, valve means normally in a position to'permit fluid under pressure to be supplied from said communication to the said chamber and operative to a different position to prevent the supply of fluid under pressure from said communication to said-chamber and at the same time vent fluid under pressure from said chamber, a valve device having a normal position preventing the supply of fluid under pressure from said communication to said chamber and operative to a different position to cause fluid under pressure to be supplied from said communication to said chamber, means eifective when a vehicle wheel begins to-slip for causing operation of said valve means to its said different position and effective, when the pressure in said chamber reduces below'a certain degree, to restore the said valve means to its said one position so' that fluid under pressure may be resupplied to the said chamber to effect reapplication of the brakes, and means effective to cause operation of the said valve device to its said different position to cause fluid under pressure to be resupplied to said chamber to effect reapplication of the brakes upon the expiration of a certain time after the wheel begins to slip in the event that the said valve means is not sooner restored to its said one position.

7. Vehicle brake apparatus comprising, in combination, means providing a chamber, means effective in accordance with the fluid pressure established in said chamber for causing application of the brakes on a wheel of the vehicle to a degree corresponding to the pressure in the chamber, means providing a communication adapted tobe charged with fluid at a pressure corresponding to a selected degree of application of the brakes, valve means normally in a position to permit fluid under pressure to be supplied from said communication to the said chamber and operative to a different position to prevent the supply of fluid under pressurefrom said communication to said chamber and at the same time vent fluid under pressure from said chamber, a valve device having a normal position preventing the supply of fluid under pressure from said communication to said chamber and operative to a different position to cause fluid under pressure to be supplied from said communication to said chamber, means efiective when a vehicle wheel begins to slip for causing operation of said valve means to its said different position and effective when the pressure in said chamber reduces sufficiently to-cause theapplication of the brakes to reduce below a certain degree for restoring the said valve means to its said one position so that fluid under pressure may be resupplied to the said chamber to efiect reapplication of the brakes, and a doublecheck valve device selectively establishing communication through which fluid under pressure is supplied to said chamber under control of either said valve means or said valve device.

8. Vehicle brake apparatus comprising, in combination, means providing a chamber, means effective in accordance with the fluid pressure established in said chamber for'causing application of the brakes on a wheel of the vehicle to a degree corresponding to the pressure in the chamber, means providing a communication adapted to be charged with fluid at a pressure corresponding to a selected degree of application of the brakes, valve means normally in a position to permit fluid under pressure to be supplied from said communication to the said chamber and operative to a diflerent position to prevent the supply of fluid under pressure from said communication to said chamber and at the same time vent fluid under pressure from said chamber, a valve device having a normal position preventing the supply of fluid under pressure from said communication to said chamber and operative to a difierent position to cause fluid under pressure to be supplied from said communication to said chamber, means e'flective when a vehicle wheel begins to slip for causing operation of said valve means to its said different position and eflective when the pressure in said chamber reduces sufllciently to cause the application of the brakes to reduce below a certain degree for restoring the said valve means to its said one position so that fluid under pressure may be resupplied to the said chamber to efiect reapplication of the brakes, and a oneway valve interposed between the said chamber and said communication in such a manner as to 9'. Vehicle brake control apparatus compris-- ing, in combination, means providing a chamber adapted to be charged with fluid under pressure, means efiective to'cause application of the brakes on a vehicle wheel to a degree corresponding with the fluid pressure established in the chamber, means providing a communication through which fluid under pressure is supplied to said chamber and released therefrom, a magnet valve device efiective when deenergized to permit fluid under pressure to be supplied to said communication and operative to a difl'erent position, when energized, in which it prevents the supply of fluid under pressure through the communication to said chamber and at the same time vents fluid under pressure from said chamber, a relay, a pressure switch controlled according to the pressure in said chamber and operative to a closed position only so long as pressure in 'the said chamber exceeds a certain pressure, and a switch device operative to a closed position when a vehicle wheel begins to slip for causing energization of said magnet valve device and said relay, said relay and said pressure switch being jointly effective to maintain said magnet valve device and said relay energ ized independently of said switch device until said pressure switch opens in response to the reduction of pressure in said chamber caused by energization of the magnet valve device.

DONALD L. MCNEAL. 

